A Hybrid Nearest Level Combined With PWM Control Strategy: Analysis and Implementation on Cascaded H-Bridge Multilevel Inverter and its Fault Tolerant Topology

Abstract

This paper presents a hybrid control strategy which combines the nearest level control technique with PWM control technique on a cascaded H-Bridge Multilevel Inverters (MLI). MLIs have become very popular due to its several adavantages in the application areas like industrial drives and gridconnected renewable energy generation systems. With the reduced number of switches, driver circuits, conduction losses, switching losses, voltage stresses, size, and cost of the system, MLI has outperformed its two-level counterpart in terms of power quality issues. Reduction in the Harmonics and consequently the Total Harmonic Distortion (THD) in the output voltage has added to the benefits of MLI. Topological advancements in MLI require a satisfactory output voltage control strategy. In this work, a hybrid control strategy for a smooth and wider range of control of output voltage is proposed. The hybridized scheme enhances the control range of the voltage considerably. Moreover, the THD is also reduced compared to the conventional sinusoidal PWM scheme. A thorough analysis of the scheme has also been presented in the paper. SIMULINK/ MATLAB environment is used for testing the simulation model of the proposed control scheme. This hybridized controlling technique is also simulated for thermal modelling on PLECS software and power loss analysis is performed. The mathematical and simulation analyses are validated on an experimental prototype using a TMS320F28335 DSP controller card. The hybrid scheme has also been tested for a fault tolerant model of the cascaded H-bridge inverter. The performance of the hybrid scheme under different fault condition has also been shown to work satisfactorily.

A hybrid five‐level inverter configuration with improved reliability and reduced number of components

“…In addition, this topology recommends to employ a tap‐changing transformer at inverter output to maintain rated voltage, but this deals with high cost and reduced power density. An asymmetrical MLI topology developed in Sarwar et al 35 employs two redundant switches to make the circuit fault‐tolerant, which can handle all single switch faults and some multiswitch faults. However, the total standing voltage (TSV) requirement in this circuit is very high and necessitates the use of separate DC sources.…”

Crystal Structure Algorithm (CryStAl) Based Selective Harmonic Elimination Modulation in a Cascaded H-Bridge Multilevel Inverter

“…(a) High switching frequency modulation (b) Low or Fundamental switching frequency modulation. Substantial power loss occurs in the switches when the inverter is operated at a high switching frequency [6]. Hence the fundamental switching frequency scheme is preferred in high power utilities to minimize the power loss associated with the switching.…”

A Dual Source Switched-Capacitor Multilevel Inverter with Reduced Device Count

“…Furthermore, the later developed topologies outperform the three traditional topologies in component counts. Currently, researchers are developing MLIs with an application-based approach with fault-tolerance, modularity, efficiency and even weight and volume requirements in mind [5][6][7].…”